import java.math.BigInteger;
import java.util.Scanner;

public class demo04 {
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        int n=sc.nextInt();
        BigInteger num=BigInteger.valueOf(1);
        for (int i = 1; i <= n; i++) {
            num=num.multiply(BigInteger.valueOf(i));
        }
        System.out.println(num);
    }
}
